Sulfosuccinate half ester lime soap dispersing agents

ABSTRACT

A SOAP BAR HAVING IMPROVED LIME SOAP DISPERSING CHARACTERISTICS IS PROVIDED WHICH CONSISTS ESSENTIALLY OF A WATER-SOLUBLE SOAP NORMALLY HAVING POOR LIME SOAP DISPERSING CHARACTERISTICS AND A LIME SOAP CURD DISPERSANT. THE LIME SOAP CURD DISPERSANTS ARE SULFOSUCCINATE HALF ESTERS PREPARED FROM ETHOXYLATED ALCOHOLS. THE AMOUNT OF THE LIME SOAP DISPERSANT BEING INCORPORATED INTO THE SOAP BAR IS BETWEEN 10 AND 50 PERCENT BY WEIGHT BASED ON THE TOTAL WEIGHT OF SOLIDS PRESENT IN THE SOAP BAR.

United States Patent O 3,640,882 SULFOSUCCINATE HALF ESTER LIME SOAP DISPERSING AGENTS William L. Groves, Jr., Ponca City, Okla., assignor to Continental Oil Company, Ponca City, Okla.

No Drawing. Filed May 1, 1969, Ser. No. 821,074

Int. Cl. Clltl 1/12, 1/14, 9/46 US. Cl. 252-121 1 Claim ABSTRACT OF THE DISCLOSURE A soap bar having improved lime soap dispersing characteristics is provided which consists essentially of a water-soluble soap normally having poor lime soap dispersing characteristics and a lime soap curd dispersant. The lime soap curd dispersants are sulfosuccinate half esters prepared from ethoxylated alcohols. The amount of the lime soap dispersant being incorporated into the soap bar is between 10 and 50 percent by weight based on the total weight of solids present in the soap bar.

BACKGROUND OF THE INVENTION Field of the invention This invention relates to an improved soap bar. In another aspect, this invention relates to soap bars containing a combination of soap and lime soap curd dispersants which prevent the curd-forming components of hard water to form insoluble soap. More particularly, this invention relates to a soap bar consisting essentially of a water-soluble soap normally having poor lime soap dispersing characteristics and a lime soap curd dispersant which is a sulfosuccinate half ester prepared from an ethoxylated alcohol.

Brief description of the prior art The use of ordinary toilet soaps in hard water gives rise to the formation and precipitation of insoluble fatty acid salts, commonly referred to as lime soaps. These lime soaps are formed from the displacement of the sodium cation in the soap with the calcium or magnesium ions in the hard water to give the water-insoluble precipitates. These precipitated lime soaps tend to coagulate and form a curd in wash stands, bathtubs, and the like, where the curd rises to the surface of the water and adheres to the structure containing the water as a ring. Lik wise, in laundry applications the curd adheres to the clothes being washed, as well as to the surface of the washing machine and, thus, provides ineffective cleaning of the clothes being washed. Efforts have been undertaken to solve the lime soap curd formation by adding curd dispersants or using synthetic surfactants in place of the soap.

The use of synthetic surfactants in place of soap eliminates the need for a dispersant because no curd is formed by the synthetic surfactant in hard water. In most cases, however, these synthetic surfactants are more expensive than soap bars containing a curd dispersant and are more diflicult to process into bars. Therefore, new and improved curd dispersants are constantly being sought for incorporation into soap bars to eliminate the lime soap curd problem. However, care must be exercised to insure that the lime soap curd dispersant incorporated into the soap bars do not affect the washing properties of the soap and, at the same time, are equivalent to the soap in their physical characteristics, such as hardness, plasticity under pressure, workability, extrusion, film formation, solubility rate, rehardness after moisture, and the like.

OBJECT OF THE INVENTION An object of the invention is to provide a lime soap curd dispersant for incorporation into soap bars. Another object of the invention is to provide a soap bar having improved lime soap dispersing characteristics. Other objects and advantages of the invention will become apparent to those skilled in the art from a study of the following detailed description and appended claims.

SUMMARY OF THE INVENTION Lime soap formation and precipitation can be substantially avoided by incorporating into the soap, e.g., a fatty acid soap such as a tallow or coconut oil soap, an effective amount of a water-soluble lime soap curd dispersant having the general formula:

wherein R is an alkyl or alkylaryl group containing from about 10 to 16 carbon atoms, n is an integer having an average value of from about 0.9 to about 3.5, and M is selected from the group in the alkyl portions consisting of sodium, potassium, ammonium, and lithium.

The lime soap curd dispersant of the present invention is effective to inhibit or prevent curd formation without substantially impairing the foam properties of the soap. Further, I have found that an effective amount of lime soap curd dispersant which can be incorporated into the soap bar, according to the present invention, ranges from about 10 to 50 percent by weight, based on the soap and lime soap dispersing agent.

DESCRIPTION OF PREFERRED EMBODIMENTS The soap which can be used in accordance with the present invention can be any of the water-soluble curdproducing soaps which are well known. The term soap as employed in the present invention refers to the soluble metal salts of fatty acids. These soaps may be produced by the saponification of fatty materials suitable for use in soap making. Among suitable fatty materials are the fats, oils and waxes of animals, vegetables, and the fatty acids derived therefrom or of synthetic origin. More specially, the fatty acids in the C to C carbon atoms range may be derived from tallow, whereas the fatty acids in the C to C carbon atoms range may be derived from coconut oil. It is to be understood, however, that other fatty acids having a carbon atom range within the range of from about 12 to 18 which are derived from other sources, such as cotton seed oil, palm oil, palm kernel oil, and the like may be employed in the practice of this invention. However, generally, it is desirable to use the alkali metal salts of fatty acids derived from tallow, coconut oil and mixtures thereof. Desirable results have been obtained wherein the soap constituent of the sodium salts of the fatty acids having from 12 to 18 carbon atoms derived from tallow, coconut oil and mixtures thereof. The lime soap curd dispersants employed in producing a soap bar having improved lime soap dispersing characteristics are the sulfosuccinate half esters prepared from ethoxylated alcohols. These lime soap curd dispersants are represented by the general formula:

5 03M R(O oH2oH2)..ot ioH2-('J-0oM wherein R is an alkyl or alkylaryl group containing from about 10 to 16 carbon atoms, n is an integer having an average value of from about 0.9 to about 3.5, and M is a' cation selected from the group consisting of sodium,

potassium, ammonium, lithium, and the like. Examples of alkyl and alkylaryl groups which can be R in the general formula are l-decyl, l-dodecyl, l-tetra'decyl, 1-hexadecyl, 2-decyl, 4-dodecyl, 6-te'tradecyl, 8-hexadecyl, 2- butyl-l-octyl, 2-hexyl-1-decyl, dodecyl phenyl, tetradecyl phenyl, hexadecyl phenyl and the like. The sulfosuccinate half esters employed as the lime soap curd dispersant of the present invention can be prepared by any suitable manner which is known in the art. Further, I have found that alcohols containing from 10 to 16 carbon atoms and containing from about to 40 percent ethylene oxide produce the desirable sulfosuccinate half esters to be employed in the practice of the present invention. Especially desirable results have been obtained wherein the ethylated alcohols contain from about to 30 percent ethylene oxide and the alcohols contain from about 12 to 14 carbon atoms. Further, I have found that excellent results are obtained when the lime soap curd dispersants of the present invention are incorporated into soap bars in an eifective amount so as to provide to about 10 to 50 weight percent lime soap curd dispersant based on the weight of the total solids present in said soap bar, i.e., the lime soap dispersant and the soap constituents. Especially desirable results have been obtained wherein the lime soap dispersant is present in an amount of about 15 to weight percent based on the weight of these solids.

In order to illustrate further the soap bar having improved lime soap dispersing characteristics of the present invention, the following specific examples are given. The examples are presented primarily for the purpose of illustration and any enumeration or details contained therein are not to be interpreted as a limitation on the invention except as indicated in the appended claims. All parts and percentages of constituents referred to in the following examples are by weight unless otherwise indicated.

EXAMPLE 1 One mole (267.5 grams) of an ethoxylated alcohol containing 20 percent by weight ethylene oxide groups (OCH CH which had been prepared by the conventional base catalyzed reaction of ethylene oxide with a primary aliphatic alcohol having 14 carbon atoms, was admixed with 1.01 mole (99 grams) of maleic anhydride and the resulting mixture was heated and stirred at 100 C. for 3 hours in a flask equipped with a nitrogen blanketing system. The nitrogen blanket was used to prevent air from contacting the ethoxylated alcohol and turning it dark colored. One mole (365.6 grams) of the resulting ethoxylate maleate was then charged to a 3-necked, round bottom flask equipped with a stirrer, thermometer and reflux condenser. One mole (129 grams) of sodium sulfite and 837 grams of distilled water were then added to the flask and the whole was heated and stirred at 90 to 100 C. for 3 hours. The resulting sulfosuccinate half ester, having the general formula was then recovered from the reaction mixture and dried. The dried sulfosuccinate half ester was dry blended with the desired amount of commercial soap flakes or chips. The soap used in this work was the sodium salt of a blend of 80% tallow and-20% coco fatty acid. After dry blending the soap and sulfosuccinate half ester, the blend was milled through a three roll mill until homogeneous (2 or 3 passes) and then plodded through a conventional laboratory model soap plodder. The extruded product was cut and bars were stamped from it.

Evaluation of curd dispersibility was made on the bar by either of two methods. However, with method 1 the evaluation may be made on the bar components from 4 individual stock solutions without actual incorporation into a bar. The lime soap dispersing ability of the sulfosuccinates was evaluated by two methods as given below. 1

Method 1 Curd is precipitated with hard water from a solution of the bar and filtered. The soap content of the filtrate is titrated and from this the percent curd, based on original bar weight, removed in filtration is calculated. A low value for percent curd is desirable.

Method 2 A plastic dishpan was filled with warm tap water (200300 p.p.m. hardness). The experimental bars were evaluated for curd formation by washing the hands. The bars were rated as poor (curd for-med) or good (no noticeable curds).

Correlation between the two tests is not good, since one is a quantitative test and the other qualitative. Where as a low number is better than a high number in the curd filtration test, we have not established a good-poor numerical relationship. Apparently a bar may have a relatively low amount of filterable curd and show a visually undesirable curd in the dishpan test. Conversely, as high as 30% filterable curd has in some cases not produced a visually undersirable curd in the dishpan. Some inconsistencies between the two tests indicate that the visual curd may be a function of bar processing. This variable cannot eifect the filtration test. Since we obtain generally good correlation, we feel the filtration test (Method 1) is more reliable and truly representative. A value of less than 30% should represent a potentially good curd dispersant.

sulfosuccinate half esters prepared in accordance with the general methods outlined above wherein said sulfosuccinate half esters were prepared from alcohols containing 10 to 16 carbon atoms and having 20 to 40 weight percent ethylene oxide present produced desirable results which are indicated in Table I below.

* Remainder of solids in bar was a blend of coco and tallow soap.

A series of runs were also conducted wherein the half esters of the sulfosuccinate contained 10 percent ethylene oxide. Table II below illustrates the results of such experiments and indicates that, when 10 percent ethylene oxide is present in the sulfosuccinate half esters, undesirable results as to satisfactory curd dispensing properties are not obtained.

TABLE II Percent Method 1,

Ethoxylate structure in of bar percent Method suliosuccinates solids* curd 2 C12 plus 10% E0 20 59.1 Poor. 014 plus 10% E0 15 46. 4 Do.

* Remainder of solids in bar was a blend of coco and tallow soap.

EXAMPLE 2 In order to determine the effect of unreacted ethoxylate or ethoxylate maleate, hereafter referred to as free oil, bars were made up containing the soap, sulfosuccinate and free oil as designated. Data obtained from these experiments are indicated below in Table III.

* Remainder of solids in bar was a blend of coco and tallow soap.

These values show that the free oil has little effect. This is especially true in view of the normal expectation of free oil level to be well below the 25.1%, lowest level, illustrated in this example.

Therefore, it is readily apparent from the above data that sulfosuccinate half esters can be employed as effective lime soap curd dispersants in soap bars. An advantage for use of these sulfosuccinate half esters is seen in the ease of processing. Frequently, synthetic surfactants added to soap require major process changes and careful manipulation to produce a bar. These sulfosuccinate half esters present no problem as to processing. Further, associated with this property of easy processing, the bars themselves appear very much like the commercial soap bars as to both feel and appearance. Further, the bars produced containing the lime soap curd dispersant of the present invention did not suffer from the disadvantage that many synthetic additives do which tend to produce a tacky, tough, brittle or otherwise unattractive bar. The soap bars containing the lime soap curd dispersant of the present invention were totally satisfactory as to all physical properties.

Having thus described the invention, I claim:

1. A soap bar, having improved lime soap dispersing characteristics, consisting of:

(A) percent by weight of a sodium salt of a blend of tallow fatty acids and 20% coconut fatty acids; and

(B) 25 percent by weight of a lime soap dispersant having the formula:

0 SOHNB R(OCHzCH2)nOICHz-CfilONa wherein R is an alkyl group having 10 to 14 carbon atoms and n has a value of 1.2.

References Cited UNITED STATES PATENTS 3,247,121 4/1966 Hendricks 252117 FOREIGN PATENTS 1,153,303 5/1969 Great Britain 252354 1,108,410 4/1968 Great Britain 252354 1,089,797 3/1955 France 252161 6,611,798 2/ 1967 Netherlands 252354 OTHER REFERENCES Aerosol A-102 Surface Active Agent, bulletin of American Cyanamid Co., July 1967, pp. I, II, 1 and 8.

LEON D. ROSDOL, Primary Examiner D. L. ALBRECHT, Assistant Examiner U.S. Cl. X.R. 

